Activated charcoal

Activated charcoal is treated in hospitals as a medicine for certain poisonings because it binds substances in the stomach and intestines before they are absorbed. The same property is why taking it casually is a problem: it does not distinguish between a poison, a nutrient and your prescription medicine.

Activated charcoal is carbon processed to create an extremely large internal surface area, which is what allows adsorption. Products differ in surface area and particle size, and consumer capsules are not equivalent to clinical suspensions.

It works physically, not biologically: substances stick to its surface within the gut and leave with the stool instead of entering the bloodstream.

Clinical evidence supports its use in selected acute poisonings when given soon after ingestion under professional judgement. Consumer uses — detox drinks, hangover prevention, general cleansing — have no adequate supporting trials, and gas and bloating studies are small and inconsistent.

Laboratory work characterises adsorption capacity for different compounds and informs which poisonings it can help with.

Evidence gap: In-vitro adsorption data. It describes binding capability and does not support consumer detox claims.

This is the key practical issue: activated charcoal reduces absorption of many oral medicines and supplements taken around the same time, including contraceptives, thyroid medicine and antidepressants.

Common effects are black stools, constipation and nausea. The serious hazards are reduced effectiveness of essential medicines and, if it is inhaled into the lungs during vomiting, chemical pneumonitis — a recognised reason charcoal is given under professional supervision in poisoning. It must not be used in people with reduced consciousness, bowel obstruction or perforation risk. It is not appropriate as a routine supplement, and it does not treat the causes of bloating or fatigue. In suspected poisoning, call emergency services or a poison centre rather than self-administering.

Clinical suspensions are used in hospitals; capsules, tablets, powders and novelty drinks are sold to consumers.

For suspected poisoning, emergency services and poison centres direct care. For bloating or digestive symptoms, dietary assessment, review of medicines, and evaluation for conditions such as coeliac disease or intolerances are more likely to help. The liver and kidneys perform detoxification; no supplement replaces them.

Educational example: a person takes activated charcoal capsules each morning for cleansing and also takes levothyroxine and an oral contraceptive; both become less effective without any obvious warning sign. Decision factors are the timing of medicines, whether the claimed benefit exists at all, and whether a genuine digestive problem is being ignored. Questions to ask: could this reduce my medicines' effect, and is there evidence it helps my symptom? Detox marketing is a well-documented example of a mechanism being misrepresented to consumers.